1. Field of the Invention
Aspects of the present invention relate to a side case for a battery and a secondary battery using the same, and more particularly, to a side case that is coupled to a battery in a sliding manner and a secondary battery whose sides are covered with the side case.
2. Description of the Related Art
Unlike primary batteries, secondary batteries are rechargeable. secondary batteries have come into widespread use for small electronic apparatuses, such as cellular phones, personal digital assistants (PDAs), and notebook computers. In particular, lithium secondary batteries operate at a voltage of 3.6 V and are widely used as power supplies for electronic apparatuses. Lithium secondary batteries have operating voltages that are approximately 3 times higher than operating voltages of nickel-cadmium (Ni—Cd) batteries or nickel-metal hydride (Ni-MH) batteries, and lithium secondary batteries have high energy density per unit weight.
In general, the lithium secondary battery employs a lithium-based oxide as a positive electrode active material and a carbon material as a negative electrode active material. In addition, the lithium secondary battery may be formed in various shapes, such as a cylindrical shape, a square shape, and a pouch shape.
The square-shaped lithium secondary battery includes a jellyroll-type electrode assembly that is formed by spirally winding a laminated structure of a positive electrode plate, a separator, and a negative electrode plate, a can that has one side open and houses the electrode assembly, and a cap assembly that closes the opening portion of the can. Here, a combination of the electrode assembly, the can, and the can assembly is generally referred to as a bare cell, and the bare cell can be considered an independent secondary battery.
The secondary battery used for small electronic apparatuses is generally used in the form of a battery pack. The battery pack is formed by coupling the bare cell and a protective circuit module by molding and covering the coupled structure with a label or by putting the bare cell and the protective circuit module into an outer case, which is generally called a hard case.
Further, in recent years, an inner battery pack (which is generally and hereinafter referred to as an inner pack) that has a relatively simple structure and is compatible with various types of small electronic apparatuses has come into widespread use. However, since the inner pack according to the related art is manufactured by packing one bare cell, the inner pack has a relatively small amount of charge/discharge capacity, and thus does not have a sufficient amount of discharge for small and high-functionality electronic apparatuses. Therefore, the inner pack needs to be frequently charged due to rapid discharge, and the user should have several inner packs in case it is difficult to charge the inner pack.
In the inner pack according to the related art, the protective circuit board is coupled to the bare cell by molding using a molding resin. Therefore, in order to manufacture the inner pack, the following complicated process is performed: a core pack, which is a combination of the bare cell and the protective circuit board, is put into a mold; and a molding resin is injected into a molding space of the mold; the molding resin is hardened to couple the bare cell and the protective circuit board of the inner pack; and the inner pack is separated from the mold.
In such case, since it is difficult to recover the molding resin injected into the molding space of the mold, the process of injecting the molding resin should be accurately performed, which causes difficulty in manufacturing the inner pack. In addition, no matter how accurately the molding resin is injected, it is difficult to prevent non-uniform injection of the molding resin since the molding resin is in an amorphous state. As a result, the defect rate of the inner pack increases due to defects in the molding. Further, since the molding resin is viscous and is integrated with the core pack, it is difficult to repeat the process of forming the molding when defects occur in the molding.